Under normal nutritional and physiological conditions, fuel requirements of the body are met primarily by glucose and fatty acid metabolism. However, during abnormal metabolic stress, states induced by trauma such as operations or acute illnesses which lead to conditions such as sepsis, one of the effects is a decrease of fat and glucose utilization. More particularly, stress of injury in an individual, e.g., trauma or sepsis, is often accompanied by a total or partial dysfunction of the gastrointestinal tract. These critically ill individuals are often hospitalized and must receive most or all of their daily nutritional requirements passively in order to sustain protein synthesis and avoid malnutrition. Nutritional support therapy, particularly enteral tube feeding, may have advantageous effects in treating these patients.
It has been observed that patients who are critically ill, such as trauma or sepsis patients, in the intensive care unit and who are candidates for enteral nutrition by feeding tube, often do not tolerate existing, cornrnercially-available formulas well. Poor tolerance is manifested as gastrointestinal-related symptoms of abdominal pain, bloating and diarrhea. These conditions are not life threatening but preclude the patient from receiving the full nutritional prescription; in fact, the tube feeding diet is usually stopped until the symptoms improve. Patients who receive the tube feeding formula into their stomach in contrast to the small bowel may aspirate their gastric contents into the lungs. This can be a very serious, life-threatening consequence of enteral nutrition and is relatively common in the critically ill patients because of the presence of multiple infections.
Commercially available tube feeding formulas are characterized by high fat content, such as those described in U.S. Pat. No. 5,438,042. These formulations, however, can be a problem since the high fat formulas are emptied slower than low fat formulas and may contribute to pulmonary aspiration and to abdominal discomfort and diarrhea.
Although some low fat formulations have been tested, those formulas used to date which are low in fat have proteins as free amino acids, which are of poor physiologic value. These formulas are generally hypertonic to blood, normally over 450 mOs/kg H.sub.2 O. As the stomach empties hypertonic solutions slower than solutions which have an osmolality closer to blood levels, the fat content and high osmolality of the existing enteral formulas contribute to poor tolerance, delayed gastric emptying, pulmonary aspiration, poor wound healing and preclude the patient from meeting the caloric goals. Patients who do not tolerate tube feeding diets must be given total parenteral nutrtion, which is more costly, has a higher associated risk of serious complications such as serious infections, and requires expensive laboratory tests to monitor the clinical condition of the patient while receiving the therapy.
Although there are over 100 commercially-available tube feeding formulas, there are none which are low in fat and contain partially hydrolyzed protein. Most formulas contain 30% to 40% of the total calories from fat, with the remainder of the non-protein calories being carbohydrate. The fat often consists of variety of long chain triglycerides, which are difficult to digest and may contribute to diarrhea and abdominal pain. Many formulas also contain medium chain triglycerides. Medium chain triglycerides are easier to absorb, but they still empty slower than protein and carbohydrate from the stomach. There are a couple of products which are extremely low in total fats, but contain all of the protein in the form of free amino acids, rather than in the intact or partially hydrolyzed state. The free amino acids cause the osmolality of the formula to increase over formulas where protein is in the intact state. As noted, high osmolality solutions empty at a slower rate than solutions with osmolalities closer to blood, leading to potential aspiration problems. Today, there are no products on the market which are both low in fat (less than 10 grams per liter) and low in osmolality (less than 500 mOs/kg H.sub.2 O).
Thus, a need exists for an improved enteral formula which provides sufficient calories and nutrients but is low in fat and not hypertonic to blood.
Accordingly, an object of the invention is to provide an improved enteral formulation which provides high quality nutrition to critically ill patients while increasing tolerance and reducing the risk of pulmonary aspiration.
Another object of the invention is to provide a method of minimizing the risk or pulmonary aspiration and/or gastrointestinal dysfunction in critically ill patients by administering the enteral formulation of the invention which is low in fat and not hypertonic to blood.
Another object of the invention is to control blood sugar levels of critically ill patients by administering the enteral formulation of the invention which is low in fat, not hypertonic to blood and contains corn starch in the range of 1-10 grams/per liter of formulation.
A still further object of the invention is to provide a method for treating hypercatabolic patients by administering the enteral formulation of the invention which is low in fat and not hypertonic to blood.
These and other objects and features of the invention will be apparent from the following description and from the claims.